WordPress面包屑导航 BY:Dimox

面包屑是网站导航的一个重要元素，它提高了他的可用性。尤其是对于结构复杂的站点。在我用过的面包屑导航插件或者代码中，我认为只有 @Dimox 写的代码比较符合我的要求，所以我就把它复制过来备用。

原文介绍：

http://dimox.net/wordpress-breadcrumbs-without-a-plugin/

WordPress breadcrumbs function (last updated: 2019.03.03)

<?php
/*
 * WordPress Breadcrumbs
 * author: Dimox
 * version: 2019.03.03
 * license: MIT
*/
function dimox_breadcrumbs() {

	/* === OPTIONS === */
	$text['home']     = 'Home'; // text for the 'Home' link
	$text['category'] = 'Archive by Category "%s"'; // text for a category page
	$text['search']   = 'Search Results for "%s" Query'; // text for a search results page
	$text['tag']      = 'Posts Tagged "%s"'; // text for a tag page
	$text['author']   = 'Articles Posted by %s'; // text for an author page
	$text['404']      = 'Error 404'; // text for the 404 page
	$text['page']     = 'Page %s'; // text 'Page N'
	$text['cpage']    = 'Comment Page %s'; // text 'Comment Page N'

	$wrap_before    = '<div class="breadcrumbs" itemscope itemtype="http://schema.org/BreadcrumbList">'; // the opening wrapper tag
	$wrap_after     = '</div><!-- .breadcrumbs -->'; // the closing wrapper tag
	$sep            = '<span class="breadcrumbs__separator"> › </span>'; // separator between crumbs
	$before         = '<span class="breadcrumbs__current">'; // tag before the current crumb
	$after          = '</span>'; // tag after the current crumb

	$show_on_home   = 0; // 1 - show breadcrumbs on the homepage, 0 - don't show
	$show_home_link = 1; // 1 - show the 'Home' link, 0 - don't show
	$show_current   = 1; // 1 - show current page title, 0 - don't show
	$show_last_sep  = 1; // 1 - show last separator, when current page title is not displayed, 0 - don't show
	/* === END OF OPTIONS === */

	global $post;
	$home_url       = home_url('/');
	$link           = '<span itemprop="itemListElement" itemscope itemtype="http://schema.org/ListItem">';
	$link          .= '<a class="breadcrumbs__link" href="%1$s" itemprop="item"><span itemprop="name">%2$s</span></a>';
	$link          .= '<meta itemprop="position" content="%3$s" />';
	$link          .= '</span>';
	$parent_id      = ( $post ) ? $post->post_parent : '';
	$home_link      = sprintf( $link, $home_url, $text['home'], 1 );

	if ( is_home() || is_front_page() ) {

		if ( $show_on_home ) echo $wrap_before . $home_link . $wrap_after;

	} else {

		$position = 0;

		echo $wrap_before;

		if ( $show_home_link ) {
			$position += 1;
			echo $home_link;
		}

		if ( is_category() ) {
			$parents = get_ancestors( get_query_var('cat'), 'category' );
			foreach ( array_reverse( $parents ) as $cat ) {
				$position += 1;
				if ( $position > 1 ) echo $sep;
				echo sprintf( $link, get_category_link( $cat ), get_cat_name( $cat ), $position );
			}
			if ( get_query_var( 'paged' ) ) {
				$position += 1;
				$cat = get_query_var('cat');
				echo $sep . sprintf( $link, get_category_link( $cat ), get_cat_name( $cat ), $position );
				echo $sep . $before . sprintf( $text['page'], get_query_var( 'paged' ) ) . $after;
			} else {
				if ( $show_current ) {
					if ( $position >= 1 ) echo $sep;
					echo $before . sprintf( $text['category'], single_cat_title( '', false ) ) . $after;
				} elseif ( $show_last_sep ) echo $sep;
			}

		} elseif ( is_search() ) {
			if ( get_query_var( 'paged' ) ) {
				$position += 1;
				if ( $show_home_link ) echo $sep;
				echo sprintf( $link, $home_url . '?s=' . get_search_query(), sprintf( $text['search'], get_search_query() ), $position );
				echo $sep . $before . sprintf( $text['page'], get_query_var( 'paged' ) ) . $after;
			} else {
				if ( $show_current ) {
					if ( $position >= 1 ) echo $sep;
					echo $before . sprintf( $text['search'], get_search_query() ) . $after;
				} elseif ( $show_last_sep ) echo $sep;
			}

		} elseif ( is_year() ) {
			if ( $show_home_link && $show_current ) echo $sep;
			if ( $show_current ) echo $before . get_the_time('Y') . $after;
			elseif ( $show_home_link && $show_last_sep ) echo $sep;

		} elseif ( is_month() ) {
			if ( $show_home_link ) echo $sep;
			$position += 1;
			echo sprintf( $link, get_year_link( get_the_time('Y') ), get_the_time('Y'), $position );
			if ( $show_current ) echo $sep . $before . get_the_time('F') . $after;
			elseif ( $show_last_sep ) echo $sep;

		} elseif ( is_day() ) {
			if ( $show_home_link ) echo $sep;
			$position += 1;
			echo sprintf( $link, get_year_link( get_the_time('Y') ), get_the_time('Y'), $position ) . $sep;
			$position += 1;
			echo sprintf( $link, get_month_link( get_the_time('Y'), get_the_time('m') ), get_the_time('F'), $position );
			if ( $show_current ) echo $sep . $before . get_the_time('d') . $after;
			elseif ( $show_last_sep ) echo $sep;

		} elseif ( is_single() && ! is_attachment() ) {
			if ( get_post_type() != 'post' ) {
				$position += 1;
				$post_type = get_post_type_object( get_post_type() );
				if ( $position > 1 ) echo $sep;
				echo sprintf( $link, get_post_type_archive_link( $post_type->name ), $post_type->labels->name, $position );
				if ( $show_current ) echo $sep . $before . get_the_title() . $after;
				elseif ( $show_last_sep ) echo $sep;
			} else {
				$cat = get_the_category(); $catID = $cat[0]->cat_ID;
				$parents = get_ancestors( $catID, 'category' );
				$parents = array_reverse( $parents );
				$parents[] = $catID;
				foreach ( $parents as $cat ) {
					$position += 1;
					if ( $position > 1 ) echo $sep;
					echo sprintf( $link, get_category_link( $cat ), get_cat_name( $cat ), $position );
				}
				if ( get_query_var( 'cpage' ) ) {
					$position += 1;
					echo $sep . sprintf( $link, get_permalink(), get_the_title(), $position );
					echo $sep . $before . sprintf( $text['cpage'], get_query_var( 'cpage' ) ) . $after;
				} else {
					if ( $show_current ) echo $sep . $before . get_the_title() . $after;
					elseif ( $show_last_sep ) echo $sep;
				}
			}

		} elseif ( is_post_type_archive() ) {
			$post_type = get_post_type_object( get_post_type() );
			if ( get_query_var( 'paged' ) ) {
				$position += 1;
				if ( $position > 1 ) echo $sep;
				echo sprintf( $link, get_post_type_archive_link( $post_type->name ), $post_type->label, $position );
				echo $sep . $before . sprintf( $text['page'], get_query_var( 'paged' ) ) . $after;
			} else {
				if ( $show_home_link && $show_current ) echo $sep;
				if ( $show_current ) echo $before . $post_type->label . $after;
				elseif ( $show_home_link && $show_last_sep ) echo $sep;
			}

		} elseif ( is_attachment() ) {
			$parent = get_post( $parent_id );
			$cat = get_the_category( $parent->ID ); $catID = $cat[0]->cat_ID;
			$parents = get_ancestors( $catID, 'category' );
			$parents = array_reverse( $parents );
			$parents[] = $catID;
			foreach ( $parents as $cat ) {
				$position += 1;
				if ( $position > 1 ) echo $sep;
				echo sprintf( $link, get_category_link( $cat ), get_cat_name( $cat ), $position );
			}
			$position += 1;
			echo $sep . sprintf( $link, get_permalink( $parent ), $parent->post_title, $position );
			if ( $show_current ) echo $sep . $before . get_the_title() . $after;
			elseif ( $show_last_sep ) echo $sep;

		} elseif ( is_page() && ! $parent_id ) {
			if ( $show_home_link && $show_current ) echo $sep;
			if ( $show_current ) echo $before . get_the_title() . $after;
			elseif ( $show_home_link && $show_last_sep ) echo $sep;

		} elseif ( is_page() && $parent_id ) {
			$parents = get_post_ancestors( get_the_ID() );
			foreach ( array_reverse( $parents ) as $pageID ) {
				$position += 1;
				if ( $position > 1 ) echo $sep;
				echo sprintf( $link, get_page_link( $pageID ), get_the_title( $pageID ), $position );
			}
			if ( $show_current ) echo $sep . $before . get_the_title() . $after;
			elseif ( $show_last_sep ) echo $sep;

		} elseif ( is_tag() ) {
			if ( get_query_var( 'paged' ) ) {
				$position += 1;
				$tagID = get_query_var( 'tag_id' );
				echo $sep . sprintf( $link, get_tag_link( $tagID ), single_tag_title( '', false ), $position );
				echo $sep . $before . sprintf( $text['page'], get_query_var( 'paged' ) ) . $after;
			} else {
				if ( $show_home_link && $show_current ) echo $sep;
				if ( $show_current ) echo $before . sprintf( $text['tag'], single_tag_title( '', false ) ) . $after;
				elseif ( $show_home_link && $show_last_sep ) echo $sep;
			}

		} elseif ( is_author() ) {
			$author = get_userdata( get_query_var( 'author' ) );
			if ( get_query_var( 'paged' ) ) {
				$position += 1;
				echo $sep . sprintf( $link, get_author_posts_url( $author->ID ), sprintf( $text['author'], $author->display_name ), $position );
				echo $sep . $before . sprintf( $text['page'], get_query_var( 'paged' ) ) . $after;
			} else {
				if ( $show_home_link && $show_current ) echo $sep;
				if ( $show_current ) echo $before . sprintf( $text['author'], $author->display_name ) . $after;
				elseif ( $show_home_link && $show_last_sep ) echo $sep;
			}

		} elseif ( is_404() ) {
			if ( $show_home_link && $show_current ) echo $sep;
			if ( $show_current ) echo $before . $text['404'] . $after;
			elseif ( $show_last_sep ) echo $sep;

		} elseif ( has_post_format() && ! is_singular() ) {
			if ( $show_home_link && $show_current ) echo $sep;
			echo get_post_format_string( get_post_format() );
		}

		echo $wrap_after;

	}
} // end of dimox_breadcrumbs()

只需将此函数粘贴到主题的functions.php文件中（不包括<？php）然后将以下代码粘贴到主题的某个位置，面包屑必然出现在该位置：

<!--?php if (function_exists('dimox_breadcrumbs')) dimox_breadcrumbs(); ?-->

现在剩下要做的就是用CSS设计你的面包屑。可以使用.breadcrumbs设置breadcrumbs块的样式，使用.breadcrumbs_uu current设置当前crumb的样式。